The Protective Effect Of RVD2 On Acute Lung Injury Of Sepsis With Different TCM Syndromes And The Clinical Value Of Receptor Detection

Aims:To investigate the protective effect of Resolvin D2 on lung injury in CLP sepsis model mice,the mechanism of the machine molecular,and the prognostic effect of its receptor-GPR18 expression in peripheral blood PMNs of sepsis patients.Methods:Part I: to study the protective effect and molecular mechanism of Resolvin D2 on lung injury in CLP sepsis model mice.Male C57BL/6 mice were randomly divided into three groups: sham operation(SO)group;CLP group;The CLP + RVD2 group.The mice were treated with PBS and RVD2 of the same volume,and the 7-day survival rate was observed.Parallel experiments were conducted on mice treated the same way.The mice were sacrificed 24 hours after modeling.The lung tissues of mice were collected.The pathological changes and the MPO activition of the lung tissues were observed,and the molecular mechanism was explored by Western blotting.Part II: To verify on the expression of Resolvin D2 receptor-GPR18 in PMNs of sepsis patients as a prognostic biomarker.The predictive effect of GPR18-the Resolvin D2 receptor expression on PMNs in patients with sepsis: 81 patients with sepsis in ICU of tianjin nankai hospital were selected,and the GPR18 expression in PMNs in peripheral blood was detected by flow cytometry and compared with 30 healthy controls.Patients APACHEII score,SOFA score and patien-related information were recorded and statistically analyzed with the expression of GPR18.PMN was treated with different concentrations of LPS(or the same concentration at different times)and TLR4 antagonists(TAK-242).The relationship between TCM classification of "three syndromes and three methods" and the positive rate of GPR8 and the 28-day survival rate was analyzed.Results:1?RVD2 significantly extended the survival time of CLP model mice.All mice in the SO group survived to 7 days.The survival rate of CLP group was significantly decreased.Compared with the CLP group,the survival rate of CLP+RVD2 group was significantly improved,but it was still lower than that of the SO group.RVD2 alleviated the pulmonary histopathological changes induced by CLP.Three groups of mice were sacrificed at 24 h after modeling.Lung tissue was collected for HE section staining and observed under the microscope.Lung injury score in RvD2 group was significantly lower than that in CLP group.The results showed that RvD2 significantly reduced the histopathological changes induced by CLP,resulting in decreased lung injury score.After 24 hours of modeling,the MPO activity in lung tissues of CLP group was significantly higher than that of SO group,while the MPO activity in lung tissues of CLP group treated with RVD2 was significantly decreased?RVD2 reduced lung tissue permeability in CLP mice.After 24 h of modeling,the albumin level in BBALF of mice was significantly increased,and RvD2 could reduce the level.RVD2 reduced the content of TNF-?,IL-1 and IL-6 in the alveolar lavage fluid of CLP group.Compared with the SO group,the three proinflammatory factors in the CLP group were significantly increased.The RVD2 group was significantly decreased compared with the CLP group.2?The expression of RVD2 receptor-GPR18 on PMNs in peripheral blood has certain clinical value in judging the prognosis of sepsis patients.The positive rate of GPR18 is negatively correlated with the severity of sepsis and can help determine the 28-day survival rate.LPS-TLR4 signaling is involved in regulating the expression of GPR18 on PMNs:Flow cytometry revealed that the LPS treatment decreased the percentage of GPR18-positive PMNs in a dose-dependent manner.In addition,we found a time-dependent reduction in percentage of GPR18-positive PMNs treated with 10?g/ml of LPS.The TLR4 antagonist,TAK-242,blocked the reaction.Conclusions:RVD2 can significantly improve the lung injury caused by CLP in ALI mouse model.It also can reduce neutrophil infiltration,inhibit proinflammatory cytokines,and improve the survival rate of mice.The expression of RVD2 receptor(GPR18)in the peripheral blood PMN of sepsis patients was negatively correlated with the severity of the disease,and it was regulated by the LPS-TLR4 pathway.